Method and apparatus for casting straps onto storage battery plates

ABSTRACT

A method and apparatus for preparing connecting straps and end terminals for lead batteries by filling selected cavities of the mold is disclosed. The mold has cavities for casting connecting straps and an end terminal. Molten lead is filled up to an amount of lead sufficient to fill the preselected cavities of the mold. The content of the mold is brought together with inverted plate lugs of grouped battery plates to fuse the plate lugs together with the content of the mold prior to solidification. The method and apparatus includes a first mold block having three mold cavities in an upper face thereof, whereby two preselected cavities of the three mold cavities are translationally aligned to be filled with lead.

TECHNICAL FIELD

[0001] This disclosure relates to lead-acid batteries and, moreparticularly, to a method and apparatus for delivering molten lead or alead alloy to the cast-on-strap molds used in the manufacture andassembly of lead-acid batteries.

BACKGROUND OF THE INVENTION

[0002] Electrochemical storage batteries, and in particular, leadsulfuric acid storage batteries are ubiquitous in automotiveapplications. These batteries have electrochemical cells developingabout 2.1 Volts each. Generally, six of these cells are connected inseries to produce the 12 Volt battery known as an SLI (starting,lighting, ignition) battery common in automobile systems.

[0003] The cell elements comprise a series of alternating positive andnegative plates with separators positioned therebetween. The electricalconnections for the positive plates, and the negative plates as well,are typically made by a strap which connects the lugs of individualplates together. The straps are made of a wide variety of molten lead,or, more usually, lead-based alloys.

[0004] Various machines have been developed and used over the years tocast the straps onto the cell elements in a semi-continuous manner. Suchmachines have often been termed “cast-on-strap machines.” Generally,cast-on-strap (COS) machines require inserting the cell element upsidedown into a mold for the strap. The lug elements for the respectiveplates are thus positioned in a mold containing the requisite moltenlead or molten lead alloy, and the molten material is allowed tosolidify. The cell element is then removed with the cast-on-strap inplace.

[0005] Typically in COS machines, stacked battery plates and separatorsfor a plurality of cells making up a lead-acid storage battery have therespective connection lugs on the positive and negative plates of eachcell interconnected by a cast-on strap and an intercell connecting postor terminal post cast as an integral portion of each strap. Thesecasting operations are accomplished simultaneously with the cellsinverted but otherwise oriented as they are to be in the finishedbattery structure. Stacked cell elements are clamped with the plate lugsextending downward. A plurality of properly oriented mold cavities(e.g., 12 cavities for a 12V battery) are preheated then molten lead ispoured or flows into each mold cavity. The clamped cell assemblies arepositioned to immerse a portion of the plate connecting lug on eachplate in the molten mass in an appropriate connector strap cavity. Thecavities are then chilled, as by flowing water through the body of themold, and when the molded straps and posts solidify adequately they areextracted from the mold with the plates fused thereto.

[0006] Mold expense is a significant factor in machines of the typeunder consideration. It has been difficult to obtain suitable castingsin which mold forms can be produced. The variety of cell and terminalarrangements required for lead-acid batteries has further complicatedmold construction. Furthermore, the simultaneous casting operationdiscussed above necessitates large expensive molds and large castingmachines.

[0007] In accordance with the above, it is desirable to improve moldassemblies for battery strap and post cast-on machines. It is furtherdesired to decrease cycle time of battery strap and post cast-onmachines while reducing the cost and size of mold assemblies and castingmachines.

SUMMARY OF THE INVENTION

[0008] A method and apparatus for preparing connecting straps and endterminals for lead batteries by filling selected cavities of two molds.A first mold includes three mold cavities in an upper face thereof,whereby two preselected cavities of the three mold cavities aretranslationally aligned to be filled with lead to form a firststrap/post terminal configuration while the another two preselectedcavities of the first mold form a second strap/terminal configuration. Asecond mold includes three mold cavities in an upper face thereof thatform third and fourth strap/post terminal configurations depending onwhich two cavities are selected and translationally aligned to be filledwith lead. The first and seconds molds form four different strap/postconfigurations for connecting individual cells formed from the two moldsin a multi-cell battery.

[0009] In another embodiment, a method for casting straps onto storagebattery plates is disclosed. The method includes providing a source ofmolten lead, receiving a first mold block having three mold cavities inan upper face thereof in a first molding station, whereby twopreselected cavities of the three mold cavities are filled with lead,translating the mold block to align each of the two preselected cavitieswith the source of molten lead, and lowering the battery plate group orraising the mold block toward a battery plate group to dip lugs of thegroup into the two preselected cavities and allow solidification of themolten lead producing a cell for placement in a multi-cell battery.

[0010] The above-discussed and other features and advantages of thepresent invention will be appreciated and understood by those skilled inthe art from the following brief description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Referring to the exemplary drawings, which are meant to beexemplary, not limiting, and wherein like elements are numbered alike inseveral figures:

[0012]FIG. 1 is a partially broken away schematic perspective view ofthe operating elements of the apparatus in which the mold assemblies ofthis disclosure are utilized;

[0013]FIG. 2A is a top view of one exemplary mold having three cavitiesfor allowing flow of lead therethrough that cast straps in a firstconfiguration for a cell in a battery;

[0014]FIG. 2B is a top view of an exemplar complementary mold of FIG. 2Ahaving three cavities that cast straps in a second configuration foranother cell of the battery;

[0015]FIG. 2C is a side view of the mold of FIG. 2A illustratingU-shaped flanges in the first configuration extending from straps formedby the cavities;

[0016]FIG. 2D is a side view of the mold of FIG. 2B illustratingU-shaped flanges extending from straps formed by the cavities; and

[0017]FIG. 3 is a plan view of a 12V battery having six cells similar tothose shown in FIG. 2A-D illustrating electrical communication betweencontiguous cells through opposite polarity terminal connection with anintercell connector.

DETAILED DESCRIPTION OF THE INVENTION

[0018] A small cast-on strap (COS) machine in which the mold assembly 12of this disclosure is utilized is shown generally at 10 in FIG. 1 ascomprising a cast-on station 14 having a transfer station 16 forunloading lead-acid battery cells resulting from mold assembly 12, a lugburnishing station 20, a lug fluxing station 18, and a transfermechanism 22 in operable communication with a rotable receptacles 30disposed on a periphery portion of cast-on station 14. Transfermechanism 22 also allows transfer to perform burnishing and fluxingoperations at stations 20 and 18 and also loads the rotating receptacles30. In addition, transfer mechanism 22 unloads the rotating receptacles30 for further processing of resulting battery cell elements at transferstation 16. Cast-on station 14 is in further operable communication withtwo molding stations 26, 28. Controls (not shown) for the COS machine 10are automatically or semi-automatically operated to advance moldassemblies 12 produced at cast-on station 14 through other processes,such as cooling, by rotating cast-on station in a clockwise direction,for example. Transfer mechanism 22 transfers elements through theburnishing, fluxing and then on cast-on station 14. Cast-on station 14is configured to receive molding assembly 12 on cast-on station 14 foradvancement to the molding stations 26, 28 of cast-on station 14 inproper timing and sequence to result in casting cell strap and postterminals on the lugs of the positive and negative battery plates 32disposed in molding assembly 12 for each cell to connect thoserespective lugs electrically and mechanically and to form intercellconnector lugs or battery terminal posts (not shown) in appropriatespatial relationship for latter placement in a battery case.

[0019] The COS machine includes a drive means (not shown) for operablerotation of cast-on station 14. Stacks of interleaved positive andnegative battery plates 32 with suitable separators are mounted withtheir lugs extending downward and clamped together, typically by amachine operator actuating manual controls. When all plates 32 arealigned and stacked, the stack is elevated by transfer mechanism 22 andadvanced at a level to carry the lugs 34 through a rotating burnishingbrush in burnishing station 20. The stack then advances to a positionabove fluxing station 18, is stopped and lowered to dip the lugs 34 in afluxing solution. It is then raised and permitted to drain.

[0020] At an appropriate point in the cycle of machine control, the moldassembly 12 is preconditioned for casting. The stack is then advanced inits elevated condition from the fluxing station 18 to the cast-onstation 14. In a preferred embodiment, transfer mechanism 22 is a robotconfigured to provide suitable transfer functions outlined above. Thecast-on station 14 rotates toward molding stations 26, 28 to immerselugs 34 in molding assembly 12 for injecting molten lead in selectedmold cavities for the connector straps and post terminals. It will beappreciated that although injection of lead is discussed, other methodsto fill the mold cavities can be used. For example, mold assembly isoptionally filled by, but is not limited to, dipping or by selectivelypouring molten lead in the mold cavities.

[0021] Coolant is circulated through jackets around the mold cavities tofreeze the posts and straps and when an appropriate temperature has beenachieved the cast post and strap are extracted from their molds bysimultaneous operation of extractors driven by a knock-out plate insynchronism with the stack elevator. The cell unit with straps and postterminals are then rotated along in one of receptacles 30 to thetransfer station 16 where, for example, the machine operator releasesthe molded cell from the mold assembly 12. In one arrangement a moldedcell is then inserted into a case where individual cells are laterelectrically and mechanically joined via the straps to form intercellconnections.

[0022] The cast-on process outlined utilizes a mold filling techniquereferring to FIGS. 2A-2D. Two different configurations of moldassemblies 44 and 46 are depicted for injection of molten lead in two ofthree cavities 42 for each mold assembly 12. FIGS. 2C and 2D are crosssectional side views of mold assemblies 44 and 46 shown in FIGS. 2A and2B, respectively. Each mold produces one cell of a battery (not shown).When it is desired to inject the mold cavities 42, a lead injectionmachine (not shown) at molding stations 26, 28 is used is to injectmolten lead into two mold cavities 42, preferably simultaneously todecrease cycle time.

[0023] It will be appreciated from the preceding discussion that asubstantial degree of precision of control of thermal conditions arerequired at the cast-on station 14. The cavities must be cooledsufficiently to solidify the metal for extraction in the form of strapsand possibly a post terminal. The molten metal in the cavities cannot beso hot at the time the lugs 34 are immersed that they detrimentallyaffect the overlying cell assemblies as by melting the plates 32,separators between the plates, or the lugs 34 above the region ofimmersion.

[0024] One form of an exemplary mold assembly 12 which affords twodifferent configurations for a cell is shown in FIGS. 2A and 2Cgenerally at 44. A second form of an exemplary mold assembly whichaffords two more alternative configurations for a cell is shown in FIGS.2B and 2D generally at 46. By filling two contiguous cavities 42 of thethree cavities 42 in each mold assembly, two different configurationsfor each mold 44, 46 result depending on which two contiguous cavities42 are selected. It will be understood that each mold assembly istranslatable up and down relative to FIGS. 2C and 2D, as well as beingtranslatable in left and right directions as shown relative to FIGS.2A-2D for selecting two of the three cavities to be filled.

[0025] Referring to FIG. 3, mold cavities 42 in six individual moldsassemblies 12 for a six cell battery 48 are shown including cavities fora negative terminal post 51, a first cell negative strap 52 and apositive strap 53, a second cell positive strap 54 and negative strap55, a third cell negative strap 56 and positive strap 57, a fourth cellpositive strap 58 and negative strap 59, a fifth cell negative strap 61and positive strap 62, a sixth cell positive strap 63 and negative strap64, and a positive terminal post 65. The cavities 51 and 65 for theterminal post are continuous with the cavities 52 and 63 of the firstand sixth cells for the connector straps of the appropriate polarity.All other connector strap cavities include an intercell connector postcavity 66 adjacent a similar post cavity for the strap of oppositepolarity for the next cell whereby the connection of adjacent connectorposts connect the battery cells in series electrically. Intercellconnector post cavity 66 molds a U-shaped flange 68 that extendssubstantially perpendicular from one end of a molded strap 53-62, and64. U-shaped flange 68 is long enough to extend through slots configuredin an inner cover or partition wall (not shown) within a batterycase(not shown) for electrically joining contiguous straps of oppositepolarity by, welding, for example.

[0026] Referring to FIGS. 2A-D and 3, it will be recognized that sixcells forming battery 48 in FIG. 3 include three cells formed using moldassembly 44 and the other three cells formed using mold assembly 46.More specifically, the first cell (1) of battery 48 is formed byinjecting the two leftmost cavities of mold assembly 44 in FIG. 2A,forming negative terminal post 51, first cell negative strap 52 andpositive strap 53. The second cell (2) is formed by injecting the tworightmost cavities 42 of mold assembly 44 in FIG. 2A, forming secondcell positive strap 54 and negative strap 55. The third cell (3) isformed by injecting the two rightmost cavities 42 of mold assembly 46 inFIG. 2B, forming negative strap 56 and positive strap 57. The fourthcell (4) is formed by injecting the two rightmost cavities 42of moldassembly 44 in FIG. 2A, forming positive strap 58 and negative strap 59.The fifth cell (5) is formed by injecting the two rightmost cavities 42of mold assembly 46 in FIG. 2B, forming negative strap 61 and positivestrap 62. The sixth cell (6) is formed by injecting the two leftmostcavities 42 in FIG. 2B, forming positive strap 63 and negative strap 64,and positive terminal post 65. By translating mold assemblies 44, 46 inright and left directions, two of the three cavities 42 may be selectedto inject molten lead to provide the desired strap/post configurationfor each cell of battery 48.

[0027] Still referring to FIGS. 2A-2D, the mold assemblies 12 furtherinclude end bosses 69 and 71, ends 72 and 73 and sides 74 and 75. Amounting cavity 77 is provided in each of the bosses to enable themolding assembly to be clamped in the cast-on station 14 by means (notshown).

[0028] After filling is complete, for example, as determined by a timerset for the rate of molten metal flow, the molten metal solidifies inthe preselected cavities and mechanically and electrically joins theisolated straps to corresponding lugs. The resulting cell unit isextracted from the mold assembly 12 and transferred for furtherprocessing. Six cell units are disposed in a 12 V battery case havingflanges 68 aligned with holes in the cell partition walls within thebattery case. Contiguous flanges 68 are then electrically connected,e.g., by welding, to complete a series connection between adjacentcells.

[0029] Referring now to FIGS. 1-3 an exemplary method for manufacturinga six cell storage battery using mold assemblies 44 and 46 will beprovided. In a first cycle, molding station 26 is provided mold 44 whilemolding station 28 is provided mold 46 for simultaneously molding cellnumbers 1 and 6 having post terminals 51 and 65, respectively. Cells 1and 6 (see FIG. 3) are produced by injecting lead in the two leftmostcavities of molds 44 and 46 in the first cycle. In latter second andthird cycles, molds 44 and 46 are injected in the two rightmost cavitiesfor producing cells 2-5 of the six cell storage battery. Morespecifically, injecting the two rightmost cavities of mold 44 producesthe strap configuration needed for cells 2 and 4 while injecting the tworightmost cavities of mold 46 produces the strap configuration need forcells 3 and 5. After the three cycles using two molds 44, 46, six cellsare produced having post/strap configurations cast on for placement in abattery case and for mechanically and electrically joining contiguouscells by welding contiguous flange extending from corresponding straps.Thus, it will be recognized that mold 44 produces two post/strapconfigurations depending on which two cavities 42 are selected for leadfill. It should be pointed out that the two configurations from mold 44are different from the two configurations resulting from mold 46. Mold46 produces another two post/strap configurations depending on which twocavities 42 are selected for lead fill.

[0030] It will be understood by one skilled in the pertinent art thatthe apparatus and method discussed above for use in manufacturing cellsof a12 V battery is optionally employed in the manufacture of cells foruse in a 36 V battery. A 36 V battery includes a battery housing or casedefining a receiving area that is configured to receive and engageeighteen cells. Each cell has a plurality of positive plates each havinga positive tab portion or lug depending outwardly from a periphery, aplurality of negative plates each having a negative tab portion or lugdepending outwardly from a periphery, and a nonconductive separatordisposed in between the plurality of positive plates and the pluralityof negative plates. The tabs or lugs for the plates are analogous tolugs 34 of battery plates 32 discussed above in reference to a 12 Vbattery.

[0031] Accordingly, the above described method and apparatus affordscasting straps to individual cells for use in a battery with a smallerand less expensive mold, as well as allowing a smaller COS machine to beemployed because of the smaller mold. In addition, each mold providestwo configurations for use in connecting lugs of contiguous cells of abattery depending on the cavities selected to fill with molten lead. Theabove described method and apparatus allows more flexibility and allowsa single COS machine to mold the totality of cells to be employed in abattery. By using two COS machines in conjunction with 2 molds, cycletime can be gained.

[0032] While preferred embodiments have been shown and described,various modifications and substitutions may be made thereto withoutdeparting from the spirit and scope of the invention. Accordingly, it isto be understood that the apparatus and method have been described byway of illustration only, and such illustrations and embodiments as havebeen disclosed herein are not to be construed as limiting to the claims.

What is claimed is:
 1. A mold for preparing connecting straps and endterminals for lead batteries by filling the mold, which has cavitiescorresponding to the connecting strap and to the end terminal, withmolten lead up to an amount of lead sufficient to fill the mold, and bybringing the content of the mold up from the bottom and together withinverted plate lugs of grouped battery plates, to fuse the plate lugstogether with the content of the mold prior to solidificationcomprising: a first mold block having three mold cavities linearlyaligned in an upper face thereof, whereby two preselected cavities ofthe three mold cavities are translationally aligned to be filled withlead.
 2. The mold of claim 1 wherein the three cavities comprise a firststrap cavity configured to form a first strap, a second strap cavityconfigured to form a second strap, and a third post terminal cavityconfigured to form a first post terminal.
 3. The mold of claim 2 whereinthe first and second straps are configured having an extension tabextending substantially perpendicular thereto, each extension tabextending from an opposite end of a respective strap of the first andsecond straps.
 4. The mold of claim 3 wherein first and second strapsare contiguous on the mold block.
 5. The mold of claim 4 furthercomprising a second mold block, wherein the second mold block includesthree cavities, the three cavities further comprise a fourth strapcavity configured to form a fourth strap, a fifth strap cavityconfigured to form a fifth strap, and a sixth post terminal cavityconfigured to form a second post terminal, the fourth and fifth strapsare contiguous and each strap includes the extension tab in an oppositeorientation of the first and second straps, respectively.
 6. The mold ofclaim 5 wherein first and second molds provide four differentconfigurations of strap and terminal connectors.
 7. The mold of claim 5wherein six cell elements are manufactured in three cycles using firstand second molds with two molding machines.
 8. The mold of claim 1wherein the source of molten lead is a lead injection machine.
 9. Anapparatus for casting elements onto storage battery plates comprising; asource of molten lead; a first mold block having three mould cavitieslinearly aligned in an upper face thereof, whereby two preselectedcavities of the three mold cavities are filled with lead; means fortranslating the mold block to align each of the two preselected cavitieswith the source of molten lead; and means for engaging the mold blockwith a battery plate group to dip lugs of the group into the twopreselected cavities.
 10. The apparatus of claim 9 wherein the threecavities comprise a first strap cavity configured to form a first strap,a second strap cavity configured to form a second strap, and a thirdpost terminal cavity configured to form a first post terminal.
 11. Theapparatus of claim 10 wherein the first and second straps are configuredhaving an extension tab extending substantially perpendicular thereto,each extension tab extending from an opposite end of a respective strapof the first and second straps.
 12. The apparatus of claim 11 whereinfirst and second straps are contiguous on the mold block.
 13. Theapparatus of claim 12 further comprising a second mold block, whereinthe second mold block includes three cavities, the three cavitiesfurther comprise a fourth strap cavity configured to form a fourthstrap, a fifth strap cavity configured to form a fifth strap, and asixth post terminal cavity configured to form a second post terminal,the fourth and fifth straps are contiguous and each strap includes theextension tab in an opposite orientation of the first and second straps,respectively.
 14. The apparatus of claim 13 wherein first and secondmolds provide four different configurations of strap and terminalconnectors.
 15. The apparatus of claim 13 further comprising two moldingmachines wherein six cell elements are manufactured in three cyclesusing first and second molds with the two molding machines.
 16. Theapparatus of claim 9 wherein the source of molten lead is a leadinjection machine.
 17. A method for casting elements onto storagebattery plates comprising; providing a source of molten lead; receivinga first mold block having three mold cavities linearly aligned in anupper face thereof in a first molding station, whereby two preselectedcavities of the three mold cavities are filled with lead; translatingthe mold block to align each of the two preselected cavities with thesource of molten lead; and raising the mold block toward a battery plategroup to dip lugs of the group into the two preselected cavities. 18.The method of claim 17 wherein the three cavities comprise a first strapcavity configured to form a first strap, a second strap cavityconfigured to form a second strap, and a third post terminal cavityconfigured to form a first post terminal.
 19. The method of claim 18wherein the first and second straps are configured having an extensiontab extending substantially perpendicular thereto, each extension tabextending from an opposite end of a respective strap of the first andsecond straps.
 20. The method of claim 19 wherein first and secondstraps are contiguous on the mold block.
 21. The method of claim 20further comprising a second mold block, wherein the second mold blockincludes three cavities, the three cavities further comprise a fourthstrap cavity configured to form a fourth strap, a fifth strap cavityconfigured to form a fifth strap, and a sixth post terminal cavityconfigured to form a second post terminal, the fourth and fifth strapsare contiguous and each strap includes the extension tab in an oppositeorientation of the first and second straps, respectively.
 22. The methodof claim 21 wherein first and second molds provide four differentconfigurations of strap and terminal connectors.
 23. The method of claim22 further comprising using first and second molds with two moldingmachines wherein cell elements are manufactured in half the cycle time.24. The method of claim 17 wherein the source of molten lead is a leadinjection machine.
 25. The method of claim 23 wherein the cell elementsproduced are disposed in a battery case wherein each extension tab isaligned with holes in cell partition walls within the battery case, eachextension tab aligned with another extension tab in a contiguous cellfor electrically joining tabs extending in contiguous cells together toprovide a series connection between the cells of the battery.